U.S.-CANADA BORDER DISPUTES IN GRAINS: DYNAMIC INTERFACE BETWEEN THE FREE TRADE AGREEMENT AND TRADE REMEDY LAWS

Agricultural trade between the United States and Canada has been contentious since the inception of the CUSTA agreement in 1989. Even though Canadian exports of wheat and barley are not found to have violated U.S. trade remedy laws, friction seems likely to continue as long as the surge in Canadian exports remains unabated. Gradual harmonization of trade policies, farm subsidy programs, and marketing institutions may reduce trade disputes between the two countries in the future. To diffuse the threat of future trade disputes, a Canada - U.S. joint research team should be formed to deal with the matter through better understanding for causes of the disputes.bilateral trade, free trade agreement, trade disputes, trade remedy laws, farm income, farm price, harmonization, International Relations/Trade,

United States and Canadian Free Trade Agreement: Economic Implications

International Relations/Trade,

Enhanced protein kinase C activity correlates with the growth rate of malignant gliomas in vitro

Journal ArticleDirect measurement of protein kinase C (PKC) activity in vitro revealed a significant increase in the activity of the enzyme in all human malignant glioma lines examined and the rat C6 tumor in comparison with control nonneoplastic astrocyte and mixed glial cultures. The total and particulate PKC activity in these cell types correlated strongly [r = 0.98 (P< 0.001) and 0.94 (P = 0.002), respectively] with the maximal growth rates as measured by 3H-thymidine incorporation in each of the samples. An alteration in the growth rate of an individual glioma line (A 172) by varying the serum concentration in the growth medium produced comparative changes in the measured PKC activity. The addition of the phorbol ester phorbol-12-myristate-13-acetate to this tumor line under high serum conditions produced down-regulation of the enzyme, which was accompanied by a corresponding reduction in thymidine incorporation. The administration of the PKC inhibitor staurosporine produced a dose-related decrease in the basal proliferation rate of glioma lines A172 and C6, as measured by 3H-thymidine uptake and confirmed by flow cytometry, indicating that the high intrinsic PKC activity is amenable to pharmacological manipulation. Cytofluorometric deoxyribonucleic acid cell cycle analysis of the tumors treated with PKC modulators demonstrated that reduced proliferation rates were caused by an inhibition of entrance into the deoxyribonucleic acid synthesis (S) phase (decrease in proliferative index), supporting the evidence that these modulators are not slowing the tumor growth in a nonspecific cytotoxic manner. The data support the hypothesis that intrinsic high PKC enzyme activity correlates with the rapid proliferation rates observed in malignant gliomas and thereby implicate PKC as an important biochemical and functional marker of neoplastic glia